Radiation survey training apparatus

ABSTRACT

12. RADIATION SURVEY TRAINING APPARATUS COMPRISING: A RADIO TRANSMITTER INCLUDING MEANS TO GENERATE A CONTINUOUS SUCCESSION OF RADIO FREQUENCY OSCILLATIONS IN TRANSMITTED RADIO SIGNALS, A RISE AND DECAY CONTROL UNIT OPERABLE TO VARY THE SIGNAL STRENGTH OF SAID OSCILLATIONS IN RESPECTIVE STAGES OF RINSING AND DECAYING SIGNAL STRENGTH SIMULATING THE INTENSITY OF NUCLEAR RADIATION LEVELS DURING RISE AND DECAY OF NUCLEAR FALLOUT EMISSION, AND SELECTOR MEANS FOR SELECTIVELY OPERATING SAID RISE AND DECAY UNIT TO ENABLE OPERATION OF THE APPARATUS TO PROVIDE OUTPUT TRANSMISSION AS WELL AS TO CONFINE THE OPERATION OF THE APPARATUS TO SIMULATE EITHER A RISE OR A DECAY OF FALLOUT EMISSION.

March 2, 1971 B. c. SHAW ETAL Re. 27,078

RADIATION SURVEY TRAINING ARPARATUS Original Filed July 27, 1964 3Sheets-Sheet 1 17544144041 Y Mme/w AIME/V673 CONTROL CR YJTAL w. w m B 0z x, u 21.x, mm w m EWITMHP HMZEH I m AM w QM m l fiT. I m m M A w M L hA H L vm m u n March 2, 1971 B. c. SHAW EI'AL Re. 27,078

mumnon SURVEY TRAINING APPARATUS 3 Sheets-Sheet 2 Original Filed July27, 1964 D20 PZOU WVENTORS EMMMW (ml/m Jimv 110mm: 12 Mknamrln.data-{fit Arman/m umi EOum March 2, 1971 SHAW ETAL Re. 27,078

RADIATION SURVEY TRAINING APPARATUS Original Filed July 27, 1964 aSheets-Sheet s" EOFQJ DQUR M0350) h8 0 EMFME GNU NJ Q INVENTORS flaw/ml(AMA/01.5}? J'mw l/OWARD l filo/swung we MW e! Arron/vex? United StatesPatent Oflice Re. 27,078 Reissued Mar. 2, 1971 Int. Cl. G09]: 9/00 U.S.Cl. 35--1 21 Claims Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specifi cation; matterprinted in italics indicates the additions made by reissue.

This invention relates to training apparatus and has as its generalobject to provide a complete kit for performing field training exercisesin radiological surveys for training operators in the use of radiationdetecting equipment.

A principal object of the invention is to provide an apparatus whichwill be both safe and relatively inexpensive in its construction and useas compared to the dangers and the cost that would be involved in theproduction and detection of actual nuclear radiation. Accordingly, theinvention provides a training apparatus which will simulate theconditions arising from a nuclear explosion and the detection of theresulting radiation.

In general, the invention utilizes a set of transmitting and receivingapparatus for the transmission and reception of high frequency radiowaves simulating various types of nuclear radiation such as gamma rays[particles] and alpha particles.

Toward the attainment of the foregoing, the invention provides atraining apparatus:

(1) Which is relatively compact and highly portable;

(2) Which is battery-operated and can therefore be set up and operatedin remote areas and without the necessity for being attached to anexternal source of electric power;

(3) Embodying a transmitter having directional transmission such as todevelop a characteristic elongated oval pattern simulating that ofnuclear radiation fallout;

(4) Embodying a combination of transmitter and receiver so constructedand correlated in their operation that the received signals, asdisplayed on indicator apparatus, will simulate the indication of actualnuclear radiation as received by nuclear radiation detecting equipment.

(5 Embodying a transmitter which is adapted to transmit a series ofnuclear radiation-simulating signals with a rise and fall in intensitycorresponding to the rise and fall in the intensity of actual nuclearradiation resulting from a nuclear explosion;

(6) Adapted to transmit signals combining such rise and fall ofintensity with a distribution of the signals in a pattern simulating aradiation fallout pattern;

(7) Embodying a transmitter having selector means for effecting any oneof four transmitting operations, namely (1) under manual control, at acontrollable signal intensity variation rate; (2) consisting of a stageof automatic rising variations of signal intensity at a linear rate; (3)consisting of a stage of automatic decay of signal intensity at anexponential rate; or (4) combining rise and decay stages in a continuousautomatic operation;

(8) Embodying a transmitter having means for transmitting (in additionto its radiation-simulating signals) identification signals (e.g. callletters) for identifying the user of the apparatus. Such identificationcan be in terms of the SOC-licensed call letters of a civilian defenselicensee or a military unit having a military license;

(9) Utilizing solid-state elements in its circuitry, so as to attainmaximum reliability and long trouble-free operation;

(l0) Embodying mechanism for simulating the alpha particle radiationdeveloped where an accident (without a nuclear explosion) occurs in thetransportation of a nuclear war head, spilling nuclear material over arelatively small area (e. g. of 200 to 300 feet radius) resulting inwhat is commonly termed a hot-spot" contamination which requires adecontamination operation in order to eliminate the radiation hazard.For this purpose, the apparatus includes a hot-spot transmitter, and areceiver correlated therewith so as to obtain a reception whichsimulates reception of actual alpha particles on an alpha particledetector instrument.

In general, the invention provides a kit embodying the followinginstruments:

(a) A main transmitter for simulating radiation from fallout debris of anuclear explosion.

(b) An antenna for the main transmitter.

(c) One or more hot-spot" transmitters for simulating radiation fromnuclear material spilled from a nuclear warhead involved in an accidentduring transportation (in which a safety explosive device will blow thesections of nuclear material apart to prevent them from accidentallycoming together in sufiicient aggregate volume to trigger a nuclearexplosion).

(d) Portable simulated radiacmeters (gamma receivers) and alphacounters.

(e) Accessories.

Other objects and advantages will become apparent in the ensuingspecification and appended drawing in which:

FIG. 1 is a perspective view of the main transmitter;

FIG. 2 is a perspective view of the special antenna for developing theradiation fall-out pattern;

FIG. 3 is a block diagram of the main transmitter;

FIG. 4 is a block diagram representative of both the alpha counter andthe gamma receiver;

FIG. 5 is a diagram illustrating the simulated fallout pattern ofwave-radiation by the main transmitter;

FIG. 6 is a perspective view of the hot-spot transmitter;

FIG. 7 is a schematic diagram of the rise-decay unit of the maintransmitter; and

FIG. 8 is a schematic diagram of the electronic mechanism of thereceiver units of the apparatus.

The main transmitter (FIGS. 1 and 3) comprises generally a portableapparatus provided with a casing 19 and a hinged cover 20 for closingthe same to protect the apparatus from the elements etc.; a signalgenerating unit 22; an identification coder unit 23; a rise and decayunit 24; a power supply unit 25 (shown only in FIG. 3); a battery unit26; and miscellaneous accessories such as attachment cords, cables, etc.Such accessories are contained in a compartment 27, and the units 2326are mounted within respective compartments which as seen in FIG. 1, areintended to designate the respective operative units schematically.Since some of these units are per se of conventional construction, theyare not illustrated or described herein in detail, with the exception ofthe signal generator unit, the rise and decay unit, the receiver units,and the directional antenna, which are described in detail hereinafter.

The transmitter delivers a signal to a directional antenna 28 whichtransmits in the fallout-simulating pattern shown in FIG. 5.

The directional antenna 28 (FIG. 2) comprises a plu rality of sections(largely tubular) which are assembled in the field and which include amast section 30, a vertical radiator 29 superimposed upon the mastsection 30 in axial alignment therewith; a hub 32 for coupling thevertical radiator 29 to the mast 30; three horizontal groundplaneradials 33, disposed within a sector of the circular area on one side ofhub 32, and a pair of downwardly inclined radials 34 disposed within thesector on the opposite side of the hub. The five radials subtend equalangles as viewed in plan, approximately 72 apart.

In the operation of our improved antenna, the waves generated betweenthe vertical radiator 29 and the ground plane defined by the threehorizontal radials 33 are of greater intensity (because of the smallerangle 90 subtended between the vertical radiator and this plane) thanthe waves generated between the vertical radiator and the two downwardlyinclined radials 34 (subtending an obtuse angle). The stronger waves areprojected to a greater distance than the weaker waves, and consequentlythe transmission pattern is an ellipsoid as indicated at 35 in FIG. 5,the major axis 36 of the ellipsoid being aligned with the central radialof the horizontal group of radials 33. Despite the fact that the twolateral radials 33 extend more laterally than they do parallel to thismajor axis, the width of the pattern 35 is considerably less than itslength along the major axis 36. The pattern satisfactorily resembles afallout pattern developed by the resultant of vertical settling ofradiation particles (from a nuclear explosion) and a prevailing airmovement in a given direction.

The main transmitter components, in detail, are as follows:

The signal generator 22 (designated RF DECK in FIG. 3) comprises acrystal-controlled, transistorized oscillator 40 adapted to generate aradio-frequency oscillating current which is fed, as indicated by thesignal-flow arrow 39, to a driver amplifier 42 adapted to have its powerlevel varied by an external ultimate control device which is indicatedschematically as a variable resistor at 43. The ultimate control device43 constitutes a portion of the mechanism of the rise and decay unit 25,hereinafter described. The output of driver amplifier 42 is fed, asindicated by signal-flow arrow 44, to a power amplifier 45. The outputof the power amplifier 45 is fed, as indicated by signal flow arrow 48,to a low pass filter 4-9 which functions to remove any undesirableharmonics or spurious emissions from the signal, and which transmits afiltered signal through a conductor to the antenna 28.

The coder unit 23 (FIG. 3) functions to interrupt the operation of thepower amplifier 45 in a selected interruption pattern (e.g. such as totransmit a code signal repeated three times and then stopped). Thecontrol from the coder 23 is transmitted to the power amplifier 45through a circuit indicated schematically by the signal-flow arrow 46.The coder 23 not only controls the signal generator 22 but it alsoeffects a control over the rise and decay unit 24, transmitting thiscontrol through a circuit indicated schematically by broken line 47.During such time as the coder is in operation, the circuit 47 disablesthe rise and decay unit 24 and causes the signal generator 22 to operateconstantly at full power.

Coder unit 23 (FIG. 1) comprises a fractional horse power electric motor(not shown) driving a coding disc 90 and a gear pinion 92, the disc 90having a plurality if peripheral actuator teeth 93 adapted to actuate a01- lower lever 94 of a normally open switch 95 which functions totransmit the coder control to the filter unit 49 of the maintransmitter, effecting a dot pulse transmission when closed by a tooth92. Disc 90- may also include a series of teeth 98 separated only bynarrow saw cuts and collectively constituting a long tooth fortransmission of a dash" pulse. Disc 90 also includes a continuous raisedsection 97 on which the switch lever 94 rests when the coder is not inoperation, so as to keep the line 46 to the power amplifier 45 closed(thereby keeping the amplifier 45 operative). When the switch lever 94drops into a notch between teeth 93 or onto a low portion of theperiphery of disc 90, it renders the amplifier 45 inoperative, the line46 being an essential connection in the operating circuit of amplifier45.

The coder further includes a release lever 96 on which the switch 95 andits actuator lever 94 are carried, the

assembly of switch and the two levers being pivoted to the case asindicated. Release lever 96 is spring-loaded as indicated to yieldinglyhold the switch lever 94 normally in yielding engagement with coder disc90. The end of lever 96 is exposed for finger tip engagement to manuallywithdraw the lever and switch assembly away from the disc for servicingoperations (interchange of one coder disc by another). The coder disc asoriginally furnished to the customer has a circular periphery which iscontinuous except for a large number of the saw cuts extendingthroughout its circumference except for the continuous raised portion95. The small segments between the saw cuts are then removed by thecustomer, leaving only those segments which become the dot teeth 93 andthe dash teeth 98.

Gear pinion 92 drives a gear 99 which carries an actuator pin 100engageable with a common actuator lever for a superimposed pair ofnormally closed switches 102, 103 so as to open both of them. This isthe normal position of gear 99, in which the connection 47 from thecoder unit to the rise and decay unit 24 is inoperative. When during theoperation of the coder unit, the pin 100 orbits away from switch 102,the latter, which constitutes part of the disabling connection 47between coder 23 and rise-decay unit 24, completes a circuit whichshorts out the unit 24, rendering it inoperative. The gear ratio betweendrive pinion 92 and gear 99 is an integral ratio, a ratio of 1:3 beingpreferred though not essential.

Switch 103, when closed during the coder operation, establishes aholding circuit for the coder motor, continuing its operation through acycle ending when the pin 100 returns to its normal position, reopeningswitch 103 and thus terminating the coder operation. The operation ofthe coder unit 23 is initiated manually by a push button switch, and itis powered by a connection 104 from power supply 25. Since the coderdrive motor, its starting circuit and its holding circuit are of wellknown conventional circuitry, they are not shown in detail. In additionto the power connection 104 (12 volts) a 28 volt connection 105 isprovided between the power supply 25 and the coder 23, for powering the28 volt pulses generated by the coder and transmitted to the amplifier45 for developing coding signals for radiation from antenna 28.

Rise and decay unit 24 provides for a linear rise in the power level ofthe signal output followed by an exponential decay in accordance withthe decay properties of actual nuclear debris, where the apparatus isutilized for simulating the effect of a nuclear explosion. It is to beunderstood however that the invention is not necessarily restricted tosuch linear rise and exponential decay, but can be utilized to produce arise and fall in power level having a rate-variation other than linearrise and exponential fall, to simulate other radiation conditions whichmay require monitoring.

In the particular apparatus disclosed herein, the rise and decay controlis introduced into the circuit at the driver amplifier 42, although theinvention contemplates the possibility of applying this control at otherstages of the circuit (e.g. at the power amplifier 45). In detail, unit24, as shown in FIG. 7, comprises the ultimate control unit 43 whichtransmits the control to the driver amplifier 42 and which consists of arheostat R217 (transmitting the rise control) and a rheostat R218(transrnitting the decay control) in a combination unit in which thewipers of the two rheostats are carried by a single mount or areotherwise mechanically tied together for movement in unison over theirrespective resistor elements, as indicated by the common connectionbetween the two arrows indicating the wipers and to a conductor 55extending to the control unit 43 from a ground connection designatedGND. The same ground connection is applied to the wipers of two sectionsof a four-section manually operated gang type selector switch S203, thefour sections of which are designated by this reference charactercoupled with the respective letters A, B, C and D respectively. In theillustrated first position of this selector switch (providing for manualoperation) the ground connection is extended to a manually operablerheostat R221, through which direct manual control can be exercised foreffecting rise and fall of the power level in the driver amplifier 42without the intervention of the automatic rise-decay mechanism whichwill presently be described. In this same position, the wiper of sectionA, on its first contact, will complete a circuit to an indicator lightD5203 to indicate that the apparatus is set for manual control. Also inthis first position, the wiper of section C, on its first contact, willcomplete the power circuit from the in terminal of a twelve volt powersupply designated +12V IN through conductors 57 and 58 to a terminaldesignated +12V OUT from which the 12 volt current is supplied to theremainder of the circuit. At this point it may be noted that therise-decay unit actually utilizes only three sections of the foursection selector switch, the fourth section, D being dead and beingshown merely for the purpose of labeling the four positions of theselector switch, the manual position (just described) being labelledmanual at the section D.

In the second position of the selector switch, the circuit is adjustedfor automatic decay operation (without automatic rise), this beingdesignated simply decay" at section D. In this position, the wiper ofsection A, on its second contact, will establish a connection betweenground conductor 55 and a conductor 59 which applies ground to all ofthe remaining units of the circuit. At this point it may be noted thatin its other two positions, section A will establish the same groundconnection to the remainder of the circuit. Section B, in the secondposition, becomes inoperative (its wiper on a dead contact). Section Cof the selector switch in the second position (and also in its thirdposition) maintains the same connection through conductors 57 and 58from twelve 'volt power to the remainder of the circuit, as in the firstposition.

In the second position of selector switch S203, section B of the switchhas opened the connection from manual rheostat R221 to ground, causingthe return circuit to manual rheostat R221 to be shifted to a conductor66 which leads to a Wiper No. 1 of a gang relay K201 hereinafterdescribed in detail. In the normal position of that relay shown in FIG.7, the connection is carried on through a normally closed contact ofrelay K201 and a conductor 101 to the ultimate control rheostat R218which is the decay-control rheostat.

In the decay operation, the wiper of decay rheostat R218 starts atminimum resistance position and is gradually moved to maximum resistanceposition by the turning of shaft 61. It functions to gradually increasethe resistance in the power control circuit so as to gradually reducethe output power delivered from the driver amplifier 42 (FIG. 3) andthereby gradually reducing the power of the signal transmitted to theantenna 28. Decay rheostat R218 has a linear change of resistance withrespect to the angular displacement of its wiper drive shaft 61, so asto produce an exponential decay change in the transmitted signal. It isoperated by a return rotation of shaft 61, in the direction opposite tothe operative rotation of rise rheostat R217.

Before completing the description of operation of selector switch S203in its second position, the remainder of the circuit, which is broughtinto operation in the second position, will now be described. Conductor59 carries ground to a pair of indicator lights D8201 and D8202 whichare respectively operative to indicate the setting of the apparatus fordecay and rise operations. In the operation of the apparatus, where onlythe decay operation is being utilized, the light D3201 will remainlighted during that cycle of operation. The conductor 59 also placesground on a pair of stepping solenoids 3201A and B201B respectively,these solenoids both being coupled through a double pawl and ratchetdrive 67 to a worm and pinion gear reduction gear 60, which has a driveconnection (e.g. a continuous shaft) schematically indicated at 61, to apair of cams 62 and 63. The same drive connection, as indicated, extendsto the wipers of the two rheostats R217, R218 comprising the ultimatecontrol unit 43. The cams 62 and 63 have respective followers 64 and 65which are mechanically connected to respective switches S201 (a transferswitch) and S202 (a turn-off switch). Transfer switch S201 and turn-offswitch S202 are normally closed, spring-loaded switches which areactuated to their open positions at the ends of respective stages ofrise and decay operations by the riding of the respective cam followers64 and 65 onto the high points of their respective cams 62 and 63. Thegearing of the rise and decay solenoid unit includes not only the wormtype reduction gear 60 for transmitting rotation to the shaft 61 whichactuates the wipers of rheostats R217 and R218 in unison, but also theratchet mechanism 67 including pawls operated by the armatures of therespective solenoids and operating to transmit rotation in oppositedirections to a ratchet wheel which drives the worm. of the reductiongearing. all as schematically indicated in FIG. 5.

The remainder of the circuit which is energized when connected to groundthrough conductor 59' in the second position of selector switch S203,includes a unijunction transistor Q201 which functions at a timer toregulate the intervals between a series of pulses that are transmittedto the stepping decay solenoid B201B (in the decay operation beingdescribed), thus regulating the rate at which decay will take place. Thetiming operation of unijunc tion Q201 is under the control of a timedecay rheostat R219 transmitted through a limiting resistor R201 andtiming capacitor C201 (the latter providing a ground connection toconductor 59 to establish a time constant) and from resistor R201through a conductor 171 to a normally closed contact 17 of relay K201,thence from wiper contact 16 of that relay through a timing controlconductor 161 to the emitter of transistor Q201, for varying the timeconstant so as to adjust the rise and fall rate characteristics.

Operating power for the circuit is brought in from the 28 volt source+28V through a power bus 70 to which the time decay rheostat R219 (and arise time rheostat R220) are connected as indicated. The power line 70is continued through a power resistor R202 to base 2 of unijunctionQ201. This provides an oscillatory circuit in which unijunction Q201develops in its output circuit an oscillation which appears in the formof pulses across a resistor R203 in said output circuit. Such output ofunijunction Q201 is coupled to the base of a transistor Q202constituting a portion of a one-shot multivibrator network 71 which alsoincludes a transistor Q203 and network units comprising resistors R204,R206. R207, R208, R209 and R212; capacitors C204 and C205; and also adiode CR201, connected as indicated. Bias for transistor Q202 isestablished by resistor R206 from ground line 59, and is applied to itsbase. Bias for the transistor Q203 is developed from voltage transmittedfrom the 12 volt source through conductor 121, a biasing diode CR202 anda conductor 72; and is established on transistor 0203 by a resistorR212. The multivibrator 71 functions to expand the pulses (of spikeform) delivered by unijunction Q201 into square wave-form pulses whichare delivered by multivibrator 71 to the base of an amplifier transistorQ204 through a resistor R210. Bias on transistor Q204 is established bya resistor R213 which is connected between its base and the emitter oftransistor Q2015 through conductor 72. Current flow into transistor Q204is limited by a resistor R211 connected between its collector andground. Output voltage on the emitter of transistor Q204 is developedacross a resistor R214 and applied to the base of a transistor Q205which functions as a power switching transistor. Bias for transistorQ205 is developed from conductor 72 by a diode CR204 and is applied toits emitter. The output of power transistor Q205 is transmitted througha pulse output conductor 151 to a wiper 15 of relay K201, thence to acontact 14 of that relay on which w per 15 is normally closed, thencethrough a conductor 141 to decay solenoid B20113 for conducting powerpulses thereto. Inductive decay pulses which might otherwise bedeveloped across solenoid B201B are bled to ground through a diode CR203and ground connection 59.

In connection with the operation of this circuit on the ground positionof selector switch S203, the indicator light DS201 is energized througha conductor 131 reading from a contact 13 on which a wiper 12 of relayK201 is normally closed. Circuit to wiper 12 is completed by a conductor121 to the 12 volt power supply terminals. During the rise stage of theautomatic rise and decay operation, an alternate power-conductingcircuit is established from power inlet line 51 to connector line 121 byclosing of wiper 7 of relay K201 on its alternate contact 3 (bypassingthe power circuit through section C of selector switch 5203 alsobypassing turn-off switch S202) In the third position of selector switchS203, providing for a timed rise operation, the connections throughsections A and C thereof will remain the same but section B of thisswitch will provide a connection from ground 55 to a conductor 181leading to a terminal 18 of relay switch K201 which will thereby beenergized to reverse it, placing all of its wipers on its normally opencontacts. While parts of relay 201 have previously been referred to, thefollowing detailed description of this relay is given at this point:

Relay K201 is a six-pole double-throw relay having six wipers 6, 7, 1,12, 16 and 15 respectively (reading from the bottom of FIG. 7) andhaving active contacts as follows: for wiper 6, a normally open contact8; for wiper 7, a normally open contact 3; for wiper 1, a normally opencontact 9 and a normally closed contact 10: for wiper 12, a normallyopen contact 11 and a normally closed contact 13; for wiper 16, anormally open contact 4 and a normally closed contact 17; and for wiper15, a normally open contact 2 and a normally closed contact 14. Theenergizing coil of relay K201 is connected through a terminal 205 and aconductor 51 to the 12 volt input terminal +12V IN, thus conveying 12volt current to the relay.

When the relay K201 is energized and its wipers are shifted to thepositions alternate to those shown, wiper 15, closing on contact 2 ofthe relay, will establish a circuit from pulse output conductor 151through a conductor 21 to rise solenoid B201A so that the output pulsesdelivered from power transistor Q205 will operate that solenoid insteadof the decay solenoid. The closing of wiper 16 of relay K201 on contact4 will establish a circuit from unijunction output conductor 161 througha conductor 41 and a limiting resistor R215 to the rise time rheostatR220 so as to make that rheostat operational instead of the decayrheostat R219. At the same time, the decay time rheostat R219 has beentaken out of the circuitry by the breaking of contact between wiper 16and its contact 17. The switching of wiper 12 from terminal 11 of relayK201 turns off decay indicator light DS201 and turns on rise indicatorlight D5202, through conductor 111, now connected to 12 volt powersupply through conductor 121. The switching of wiper 1 of relay K201from its contact 10 to its contact 9 opens the circuit through conductor101 to decay rheostat R218 (thus removing that rheostat from thecircuit) and establishes connection through conductor 91 to the riserheostat R217 of ultimate control unit 43 thus making that unitoperative to control the rise function.

In the rise operation the wiper of rise control rheostat R217 starts atmaximum resistance position and is gradually moved (by the turningoperation of shaft 61) to minimum resistance position thus graduallyincreasing the power outlet of driver amplifier 42 from substantiallyzero output to maximum output with a corresponding increase of thesignal transmitted from antenna 29 from minimum to maximum power. Therise control rheostat R217 has an inversely exponential change ofresistance with respect to angular displacement of its wiper movingshaft 61 and thus produces a linear rise in the power of the transmittedsignal.

Both of the rheostats R217 and R218 operate through approximately 300 ofrotation of shaft 61 the rheostat R217 being operational when the shaftis being turned in one direction and the rheostat R218 being operationalwhen the shaft is being turned in the other direction. Selection of onerheostat or the other is made through the selective circuitryhereinbefore described.

In the fourth position of selector switch S203 providing for automaticcontinuous rise and decay operation section A of the selector switchmaintains the same connections as in the second and third position.Section B opens the circuit through conductor 181 to relay K201 thuspresetting the circuit to relay K201 for turnnig that relay off at theclose of the rise stage of automatic operation. At the same time, aholding circuit to the energizing coil of relay K201 is established fromthe wiper of section B of the selector switch through its fourth contactto a conductor 84, thence through the transfer switch S201 (which is inits normally closed position during the rise stage) thence through aconductor 81 to the normally open contact 8 of relay K201 upon which itswiper 6 is at that time closed. Thus the relay K201 is maintained in itsalternate, energized position until the end of the rise stage of theautomatic rise and decay operation.

At the end of the rise stage, the cam follower 64, actuated by therotation of cam 62, will shift the transfer switch S201 to its openposition shown in FIG. 7, opening the circuit through conductor 81 tothe energizing coil of relay K201 and causing that relay to be returned(by spring-loading means) to its deenergized position shown in FIG. 7.The holding circuit that has been temporarily set up and maintainedduring the rise stage of operation, is then opened at contact 8 of relayK201 so that it will not be reestablished at the end of the automaticoperation.

With the relay K201 returned to its normal position shown in FIG. 7, thedecay operation will proceed in the manner hereinbefore described. Inthis decay operation, the cams 62 and 63 will be rotated, in returnmovements, in the direction opposite to that in which they are rotatedduring the rise operation. The cam follower 64, backing off from thehigh point of cam 62, will permit the transfer switch S201 to reclose(without et1ecting the relay K201 since its circuit is now open atcontact 8). At the same time the cam 63 will rotate so as to move itsfollower 65 in the direction for opening the normally closed turn-offswitch S202, and at the end of the decay operation, that switch will beopened, breaking the power circuit between power conductor 51 andconnecting conductor 121. A capacitor C206, connecting conductor 181 toconductor 84, functions during the automatic rise-decay operation of theunit to provide a current surge in the line 191 to the coil of relayK201 so as to cause the relay K201 to assume the energized position whenpower is initially applied to the circuit. This capacitor is required inorder to energize the relay K201 when the power is turned on with theselector switch S203 preset in the automatic position.

The receivers (a simulated gamma ray receiver and a simulated alphaparticle counter) can be and preferably are electrically identical butare provided with different housings, one bearing indicia designatinggamma ray reception and the other bearing indicia designating alphaparticle reception. The housings externally are designed to resembleactual gamma ray and alpha particle detectors so as to make the trainingoperation most effective. Since such detectors are well known, thephysical 9 parts of the receivers are not shown. Electrically, eachreciver is shown in both FIG. 4 and FIG. 8.

Each receiver comprises an antenna 108, a radio-ire quency amplifier110; a mixer 112; a crystal-controlled oscillator 113; an intermediatefrequency amplifier 114; a voltage regulator 115; a detector 116;respective gain controls AGC2 and AGC6; and additional components whichwill be described in detail hereinafter. Gain control units AGC2 andAGC6 are hereinafter referred to only by reference to transistors Q2 andQ6 (FIG. 8) constituting the principal components thereof. Theradiofrequency amplifier, the mixer, the crystal-controlled oscillatorand the voltage regulator are of well known conventional circuitry; andthe intermediate frequency amplifier is to a large extent ofconventional type. The antenna 108 is contained entirely within thecasing of the receiver so as to avoid any external projection that woulddetract from the appearance of a conventional radiation detector. Thisis accomplished by fabricating the casing largely of molded plasticmaterial, and while some metal parts (e.g., hinges, fasteners, etc.,switch mounts and switches, etc.) are embodied in or mounted directly onor in the casing, such metal parts are connected into the antennacircuit so as to avoid weakening the received signal.

The radio frequency amplifier 110, briefly described, comprises a coilL1, impedance-matching capacitors C1 and C25 coupled to the coil toprovide a resonant circuit, loaded by a resistor R1 and connected to thebase of a transistor Q1 biased by resistors R2 and R3 from a 12 voltvoltage source +12V; transistor Q1 having a collector circuit comprisinga transformed T1 and its capacitor C4 forming a resonant circuit, andhaving an emitterbiasing circuit comprising resistor R4 and bypasscapacitor C2. The output of transformer T1 is delivered through acapacitor C6 to the mixer.

The mixer 112 comprises a transistor Q3 biased by resistors R10, R11from the 12 volt source +12V, which is bypassed at this point bycapacitor C27. Local oscillations are fed to the base of transistor Q3through a coupling capacitor C7. The collector circuit of transistor Q3comprises an intermediate frequency transformer T2. Its emitter biasingcircuit comprises capacitor C11, resistor R9 in connection to the 12volt supply +12V, and a bypass capacitor C28.

Oscillator 113 comprises a transistor Q4 having its base biased byresistors R6, R7, an emitter biasing circuit comprising resistor R8connected to the 12V voltage source, and a bypass capacitor C9; and anoscillatory collector circuit comprising a capacitor C10 and anadjustable coil L2. Feedback for the oscillator is provided by apiezo-electric crystal Y1 and a capacitor C26.

Intermediate frequency amplifier 114 comprises a transistor Qbase-biased by resistors R13, R14 and a connec tion of the latter to the12 volt source; an input connection through a coupling capacitor C13 toreceive the signal output of the mixer 112; a resistor R15 and capacitorC18 biasing the emitter; a connection to ground through resistor R18 toprovide power on its collector; and a piezo-electric resonant couplingunit Y2 coupling its output signal to the base of a transistor Q10.Transistor Q is base-biased by resistors R20 and R21 (bypassed bycapacitor C19) and a potentiometer R22 connected to the 12 volt source.Emitter bias is provided by a resistor R34 and a capacitor C20.Collector output is delivered through a piezo-electric resonant couplingunit Y3 to the base of a transistor Q11. Power for the collector currentis delivered through a resistor R33.

Transistor Q11 is base-biased through resistors R35 and R36 and isemitter-biased by a resistor R38 and a capacitor C22. Its collectorcurrent is energized by connection to ground through resistor R37 and iscoupled through a piezo-electric resonant coupling Y4 to the base of atransistor Q12.

Voltage regulator 115 is comprised of a transistor Q13 energized by aconnection to a battery indicated at 14V, through a switch S1-C when inone of its selective on" positions indicated at 5, 50 and 500(designating roentgens of radiation) and B (a battery-test position). Abase voltage is established through a Zener diode CR2 and a resistorR43. Its emitter voltage is the differential between the battery voltageand the voltage of the Zener diode, nominally 12 volts, and istransmitted to the various points in the circuit where the 12V voltageis required.

Detector 116 comprises a transistor Q12 base-biased by resistors R40,R42, and emitter-biased by resistor R41 and capacitor C23 to operate asa square-law detector (its output varying as the square of its input).Its collector is bypassed by a large capacitor C24 to remove anyshortterm variations in the collector voltage. The smoothed collectorvoltage is connected to the base of transistor Q7 (an emitter-follower)by a conductor 117. A resistor R19, bypassed by a capacitor C16,provides operating current for the base of transistor Q7 and thecollector of transistor Q12. The emitter output of transistor Q7 is fedthrough a conductor 118, bypassed by a capacitor C15, to the base of atransistor Q2 through a resistor R12. The base of transistor Q2 isbiased through a resistor R5 and bypassed through a capacitor C5. Theemitter of transistor Q2 is bypassed by capacitor C3.

The collector of transistor Q2 feeds its current to the emitter oftransistor Q1 through a resistor R4, in inverse relation to the signaloutput of transistor Q12. This relationship causes the gain intransistor Q1 to vary in a manner to oppose any change in the signalreceived from the antenna 108. It functions as an automatic gain controlwhich provides for stable operation of the meter circuit hereinafterdescribed. Supplementary gain control is provided for by a transistor Q6which receives the signal from conductor 118 through a resistor R16 andis basebiased by a resistor R17 and a capacitor C14. Collector currentoutput of transistor Q6 is fed through a resistor R15 and a capacitorC18 to the emitter of the transistor Q5 in the manner previouslydescribed for the output of transistor Q2 to the emitter of transistorQ1.

Transistor Q8 is an emitterfollower which receives a signal fromconductor 118 and develops an emitter current which is transmittedthrough a conductor 119 to a meter circuit 120.

Meter circuit 120 includes, in general, two sections (A and B) of aswitch $1, a meter M, a boost-amplifier transistor Q9, a switch S2, anda zero-setting otentiometer R-3l. Switch Sl-C, hereinbefore mentioned,is a third section of the switch S1, the three sections having a commonoperator as indicated. Potentiometer R31 functions to adjust the voltageon a conductor 122 to equal the residual voltages in the remainder ofthe circuit which appear on conductor 119 when no signal is beingreceived. Operating current is fed to the potentiometer throughresistors R30 and R32.

In the five positions of switch S1 as designated on section C thereof,section Sl-A provides a connection from conductor 119 to meter M, whichthen operates to provide an indication of the difference between thesignal potential on conductor 119 and the potential on conductor 112.The circuit to meter M is completed by a connection to the wiper ofsection B of switch S1, as shown. In the 50 position of switch S1,section A connects a resistance R25 into the circuit of meter M, inorder that the meter may read at voltage levels higher than its directreading range.

In the 500 position of switch S1, section A provides a connection 123between meter M and resistors R26 and R27 associated with transistor Q9.Resistor R26 functions to maintain the meter M within its operatingrange so long as the voltage on conductor 119 is below a valueestablished on the base of transistor Q9 by a voltage divider comprisingresistors R28 and R29. When the voltage on conductor 19 exceeds thatvalve, current flow is established to a resistor R44 to the emitter oftransistor Q9 and, through transistor action, through its collector 1 1and resistor R27. This action serves to increase the meter readings athigh signal levels to give a closer relationship between the meterreadings and the signal received on the antenna.

Switch S2 has three positions as designated, and is spring-loaded on theGAMMA middle position. In this position, and in the BETA position, theswitch has no effect on the remainder of the circuit. In the CHECKposition, it connects the voltage source 12V through a resistor R23 toconductor 119, thus placing 12 volts on meter M through resistor R23 andcausing the indicated voltage to rise in a manner to simulate the actionof a small radiation check source provided in an operational radiationdetecting instrument.

When switch S1 is in the B position, section A thereof provides a directconnection through a resistor R24 to battery, the circuit beingcompleted by a connection 124 to ground through section B of the switch.Thus the meter M becomes a voltmeter directly reading the voltage of thebattery.

A capacitor C12 provides a bypass from battery to ground so as toeliminate any internal noise voltages generated in the battery.

The hot-spot transmitter (FIG. 6) is a small, portable, self-contained,low power radio transmitter contained within a case 130 and having anextensible sectional whip antenna 132. By suitably locating the unit, itcan be used to simulate an area of high local nuclear contamination. Itis more suitable for indoor training use than is the main transmitter.It is used to provide the simulated alphaparticle field that is detectedby the alpha receiver, and may also be used to radiate to the gammareceiver. A switch (not shown) on the bottom section of antenna 132 isoperative to turn on the unit when the bottom section is extended, andto turn off the unit when the antenna is fully retracted. The hot-spottransmitter comprises circuitry generally similar to the oscillator 40and driver 42 of the main transmitter.

Operation of the apparatus may involve the use of the main transmitterfor simulating rise or decay or rise and decay radiation, with orwithout supplementary transmission from the hot-spot transmitter,coupled with the use of one or more of the gamma ray-simulatingreceivers by personnel in training, to examine the signal strength invarious portions of the area in which the transmitted signal can bereceived; supplemented by the use of the alpha receiver in the hot-spotareas of more localized transmission from the hot-spot transmitter. Itshould be noted that the signals radiated by the main transmitter and bythe hot-spot transmitter are of the same character but may vary as totheir transmission range. The signal strength of the hot-spottransmitter is not varied. The signal strength of the main transmittermay be adjusted manually by placing selected switch S203 in its firstposition as hereinbefore described; or may be varied with a linear riseeffect by placing the selector switch on its second position; or may bevaried in an exponential decay operation by placing the selector switchon its third position; or may be caused to cycle uninterruptedly througha rise stage and then through a decay stage by placing the selectorswitch on its fourth position.

In the operation of the main transmitter, the crystalcontrolledoscillator 40, operating at the. output fre quency, feeds the bufler/driver stage 42 which drives the amplifier 45 to an output of up to fivewatts into a 50 ohm load. The lowpass filter 49 inserted between thetransmitter and load greatly attenuates any second and higher orderharmonics that may be present in the transmitter output. The main 12volt power bus feeding the various main transmitter assemblies iscontrolled by the rise and decay unit 24, allowing the shutoff of allpower automatically at the completion of an exercise. The rise and decayunit 24 also controls the transmitter output power by varying theemitter resistance of the driver stage transistor (not shown). The rateand direction (increase or decrease) of power change is dictated bysettings on rise and decay front panel controls (not shown). The powersupply unit 25 is a D.C.-to-D.C. converter which supplies 28 volts tothe power amplifier through the coder. When the coder is activated, itshunts out any rise and decay unit-controlled resistance in the driverstage emitter circuit during transmit intervals, thus causing thetransmitter to operate at maximum power. During off intervals, such asspaces in the transmitted code sequence, the 28 volt supply to the poweramplifier 45 is interrupted, reducing the transmitter output toessentially zero. At the completion of an identification cycle (threetransmissions of the identifying code), the coder automatically removesthe emitter resistance short in the driver stage, returning thetransmitter power to the level dictated by the automatic rise and/ordecay program.

The rise and decay unit controls the DC. resistance in an emittercircuit in the R.F. deck 40, 42, 45 by the series combination of themanual control R221, and either the rise potentiometer, R218, or thedecay potentiometer, R217, depending upon the position of the selectorswitch, S203, and relay K201. When the selector switch is in the manualposition, only R221 controls output power. The positions of R217 andR218 are established as a function of time by a bidirectional steppermotor which is geared to the potentiometer shaft by a worm-drive systemsuch that 2500 steps are required to rotate the potentiometers throughtheir full travel. Timing periods for the stepper are established byunijunction transistor Q201, operating as a relaxation oscillator withthe period determined by an RC time constant. In the rise function, thetime constant is established by C202 and R215 in series with the risetime potentiometer R220. In thedecay cycle, the time constant isdetermined by the network consisting of C202, C201, R201 and the decaytime control R219. The timing pulse from Q2111 is coupled to theone-shot multivibrator, Q202 and Q203, which determines the duration ofthe pulse applied to the stepper. The pulse from the one-shot isamplified by Q203 and Q205 and applied to the rise stepper solenoid ordecay stepper solenoid as selected by relay K201. In the auto positionof the selector switch, transfer switch S201 is opened by a cam on theauto rise and decay potentiometer shaft at the maximum power point,causing K201, previously energized, to drop out and begin the decaycycle. At the end of the decay cycle, turn off switch S202 interruptspower to the entire main transmitter. Lamps DS201, D8202 and D5203indicate the mode of operation of the system-decay, rise or manual,respectively. The drive to the automatic rise and decay potentiometershaft is applied through a slip clutch, so that the system can bemanually overridden at any time.

We claim:

1. In a radiation survey training apparatus: means for transmittingradio signals simulating the emission from a nuclear blast fallout,comprising an antenna including a vertical radiator, a plurality ofangularly spaced horizontal radials disposed in a plane at right anglesto said radiator; and a plurality of radials disposed in a sectordiametrically opposite said horizontal radials and inclined downwardlyso as to subtend an obtuse angle with said radiator, whereby to radiatesaid signals over an area having an oval configuration simulating anuclear fallout pattern.

2. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous succession of radio frequencyoscillations for development into transmitted radio signals; means foramplifying said oscillations; a rise and decay control unit operable tovary the signal strength of said oscillations in respective stages ofrising and decaying signal strength simulating the rise and decay ofnuclear fallout emission; a selector for selectively operating said riseand decay unit so as to confine the operation of the apparatus to eithera rise stage or a decay stage of operation; said apparatus furtherincluding, in said selector, means for effecting successive stages ofrise and decay operation; and means in said rise and decay control unitto effect automatic transition from the rise stage to the decay stage.

3. Apparatus as defined in claim 2, wherein said rise and decay controlunit is operable on said amplifying means. 7

4. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous succession of radio frequencyoscillations; an amplifier for amplifying said oscillations; meansresponsive to the amplified oscillations to transmit radio signalsadapted for reception by a radio receiver in a manner to simulatenuclear radiation detection; and control means automatically operablefor varying the strength of the transmitted signals, comprising apulse-responsive stepper motor, pulse generating means for actuatingsaid motor, and means driven by said motor to vary the power level insaid amplifier.

5. Apparatus as defined in claim 4, wherein said amplifier comprises adriver stage and a power stage; and wherein said control means comprisesa variable resistor exerting a control effect on said driver stage.

6. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous successionof radio frequencyoscillations for development into transmitted radio signals; anamplifier for amplifying said oscillations; and a rise and decay controlunit operable to vary the signal strength of said oscillations inrespective stages of rising and decaying signal strength simulating therise and decay of nuclear fallout emission, said control unit comprisinga reversibly operable stepping motor; pulse-generating means foractuating said stepping motor; ultimate control means driven by saidstepper motor for varying the power level in said amplifier, comprisinga rise-control variable resistor having a resistance value varying ininverse exponential ratio to the extent of rise displacement of saidmotor so as to provide a linear rise rate and a decay-control variableresistor having a resistance value varying linearly with reference tosaid extent of displacement of said motor so as to provide anexponential decay rate; and switching means actuated by said motor foroperating said motor in one direction and for activating saidriseoontrol resistor during one stage of operation, and for operatingsaid motor in reverse direction and for activating said decay-controlresistor during a subsequent stage of operation.

7. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous succession of radio frequencyoscillations; means responsive to said oscillations to transmit radiosignals adapted for reception by a radio receiver in a manner tosimulate nuclear radiation detection; means for etfecting rise and decayvariations of signal strength; a coder operable to periodically overridethe control effect of said rise and decay means and to superimposeinterruptions on the transmission of said signals such as to convert thesame into a code signal.

8. Apparatus as defined in claim 7, wherein said coder includes means todisable said rise and decay unit so as to adjust the strength of thetransmitted code signals to the maximum for which the transmitter isset.

9. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous succession of radio frequencyoscillations; means responsive to said oscillations to transmit radiosignals adapted for reception by a radio receiver in a manner tosimulate nuclear radiation detection; means for effecting rise and decayvariations of signal strength, comprising a reversible servomotor,respective rise and decay control devices driven in opposite directionsby said servomotor and operative to vary the electrical conditions insaid transmitter so as to effect respective rise and decay of signalstrength, and a transfer switch actuated by said servomotor at the endof the rise stage of operation to disable said rise control device andto activate said decay control device.

10. Apparatus as defined in claim 9, further including a double-throw,multiple-pole relay operating under the control of said transfer switchto efiect a plurality of circuit changes in said rise and decay meansfor automatic transfer from the rise stage to the decay stage ofoperation, and a turnoff switch actuated by said servomotor to terminatea cycle of automatic operation at the end of a decay cycle thereof.

11. Apparatus as defined in claim 10, including a manual control deviceand a four-position selector switch in said rise and decay means, forselectively operating the same (1) by manual control or (2) in ahalf-cycle rise stage terminated automatically by said turnoff switch or(3) in a half-cycle decay stage similarly terminated or (4) in a fullcycle operation including said rise and decay stages joined by operationof said transfer switch and terminated by said turnolf switch.

12. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous succession of radio frequencyoscillations in transmitted radio signals; a rise and decay control unitoperable to vary the signal strength of said oscillations in respectivestages of rising and decaying signal strength simulating the intensityof nuclear radiation levels during rise and decay of nuclear falloutemission,- and selector means for selectively operating said rise anddecay unit to enable operation of the apparatus to provide outputtransmission as well as to confine the operation of the apparams tosimulate either a rise or a decay of fallout emission.

13. Radiation survey training apparatus as defined in claim 12, whereinmeans are provided enabling automatic transition of said control unitfrom the rise stage to the decay stage.

14. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous succession of radio frequencyoscillations in transmitted radio signals; and a rise and decay controlunit operable to vary the signal strength of said oscillations inrespective stages of rising and decaying signal strength simulating therise and decay of nuclear fallout emission; said apparatus furtherincluding selectively operable means for enabling successive stages ofrise and decay operation.

15. Radiation survey training apparatus as defined in claim 14, whereinmeans in said selectively operable means enables selective operation ofthe apparatus to provide output transmission simulating either a rise ora decay of fallout emission.

16. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous succession of radio frequencyoscillations; means responsive to the oscillations to transmit radiosignals adapted for reception by a radio receiver in a manner tosimulate nuclear radiation detection; and control means automaticallyoperable for varying the strength of the transmitted signals, comprisinga pulse-responsive device, a pulse generating means for actuating saidpulse-responrive device, and means driven by said device to vary thepower level in said amplifier.

17. Radiation survey training apparatus comprising: a radio transmitterincluding means to generate a continuous succession of radio frequnecyoscillations; means responsive to said oscillations to transmit radiosignals adapted for reception by a radio receiver in a manner tosimulate nuclear radiation detection,- means for efiecting rise anddecay variations of signal strength; and means for interruptingtransmission of rise and decay variations of signal strength and insteadcontrolling radio signal transmission to provide a coded signaltransmission.

18. A method of training in nuclear fallout rdliation 15 surveycomprising the steps of: simulating, by radio transmission, radio signalemissions representative of progressively rising and progressivelydecaying stages of nuclear fallout emission; directing such radio signalemissions in a pattern representative of nuclear fallout emission; andsurveying said radio signal by using radio receivers simulatingradiacmeters and alpha counters to provide a survey representative ofemission from nuclear fallout gamma particles and of alpha rays.

19. A method of training in radiation survey as defined in claim 18further comprising the steps of generating a predetermined rising signalemission simulating rise in fallout emission followed automatcally by apredetermined decreasing signal emission simulating decay in falloutemission.

20. A method of training in radiation survey as defined in claim 18further comprising the steps of providing, by auxiliary "hot spot" radiotransmissions from predetermined locations, radio signal emissionsrepresentative of high nuclear radiation auxiliary to the simulatedfallout patterns.

21. A method of training in radiation survey as defined in claim 18further comprising the step of interrupting the radio signal emission,which simulates fallout emission, and imparting via said radiotransmission a predetermined coded radio signal transmission to identifythe simulated fallout transmission.

References Cited The following references, cited by the Examiner, are ofrecord in the patented file of this patent or the original patent.

Radio Engineering Handbook, Henney, McGraw-Hill, N.Y., 1959 Edition,Chapter 18, pp. 58-60.

WILLIAM H. GRIEB, Primary Examiner US. Cl. X.R. 325-67; 343846 UNITEDSTATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Reissue No. 274378mrch 2. 1971 Inventor(s) B. C. Shaw and Howard B. Morrow, Jr.

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 3, line 58, change "if" to of Column 8, line 15, insert a commaafter operation.

Column 14, line 62, delete "a" at the beginning of line.

Column 15, line 9, "particles" should be rays and "rays" should beparticles Signed and sealed this 27th day of July 1 971 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYIER, JR. Attesting OfficerCommissioner of Patents RM PO-105O (O-69] uscoMM-Dc 5037B-Pb9 Q U 5GOVERNMENT PRINTING OFFICE Nil O!66-334

